// CRITICAL export const calcChange = (current: number, previous: number): number | null => {  if (!previous || previous === 0) return null;  return Math.round(((current - previous) / previous) * 1000) / 10;}; export const emptyResponse = (): Record<string, unknown> => ({  totals: {    total_tokens: 0,    prompt_tokens: 0,    completion_tokens: 0,    total_requests: 0,    successful_requests: 0,    failed_requests: 0,    success_rate: 0,    unique_sessions: 0,    unique_users: 0,  },  latency: {    avg_ms: 0,    p50_ms: 0,    p95_ms: 0,    p99_ms: 0,    min_ms: 0,    max_ms: 0,  },  ttft: {    avg_ms: 0,    p50_ms: 0,    p95_ms: 0,    p99_ms: 0,  },  tokens_per_request: {    avg: 0,    avg_prompt: 0,    avg_completion: 0,    max: 0,    p50: 0,    p95: 0,  },  cache: {    hits: 0,    misses: 0,    hit_tokens: 0,    miss_tokens: 0,    hit_rate: 0,  },  week_over_week: {    this_week: { requests: 0, tokens: 0, successful: 0 },    last_week: { requests: 0, tokens: 0, successful: 0 },    change_pct: { requests: null, tokens: null },  },  recent_activity: {    last_hour_requests: 0,    last_24h_requests: 0,    prev_24h_requests: 0,    last_24h_tokens: 0,    change_24h_pct: null,  },  peak_days: [],  peak_hours: [],  by_model: [],  daily: [],  daily_by_model: [],  hourly_pattern: [],}); export const toNumber = (value: unknown): number => {  const numberValue = Number(value);  return Number.isFinite(numberValue) ? numberValue : 0;}; export const getPercentile = (sorted: { latency_ms: number }[], p: number): number => {  if (sorted.length === 0) return 0;  const index = Math.floor(sorted.length * p);  return Math.round(sorted[Math.min(index, sorted.length - 1)]?.latency_ms ?? 0);};